ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
Dimmable LED 2x4 lay in fixtures
by Potseal. 04/23/17 07:18 PM
Old decora style outlets
by Lostazhell. 04/22/17 07:59 PM
Permit Snafus...AHJs and Contractors Jump in
by gfretwell. 04/22/17 01:11 PM
How do you find a good employee?
by HotLine1. 04/22/17 10:44 AM
Electrode boilers question
by SteveFehr. 04/21/17 08:32 AM
New in the Gallery:
SE cable question
Popular Topics(Views)
234,523 Are you busy
169,189 Re: Forum
162,532 Need opinion
Who's Online Now
0 registered members (), 50 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#23938 - 03/31/03 01:52 PM Raised Floor  
electrician02125  Offline
Member
Joined: Feb 2001
Posts: 89
Hi all

A couple of questions for the data center guys:

How is the raised floor grounded? Do you bond every leg or do you rely on the floor tiles to maintain this bond?

How are your PDU's grounded?


Work Gear for Electricians and the Trades

#23939 - 03/31/03 04:33 PM Re: Raised Floor  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,808
Brick, NJ USA
All the jobs that I have been on have had every other leg bonded, in a checkerboard fashion.
Cabinets are bonded to the grid.
John


John

#23940 - 03/31/03 04:47 PM Re: Raised Floor  
DBC1  Offline
Member
Joined: Mar 2003
Posts: 16
Tulsa, OK USA
I design data center's power and grounding and the answers depends if you are just looking for a code compliant method or a code compliant design method.

If it is just a code compliant method you are looking for all you have to do is ground the structure with a piece of 6 AWG to the nearest building steel or sub-panel. That is not much to go on but that is all you will get from the codebook. The PDU's are treated like any other SDS to nearest building steel and water pipes.

If you are looking for a design that gets more complicated. IEEE Emerald book gives very good details on how to construct a signal reference grid (SRG) out of the raised floor, and proper PDU terminations.

Basically I run a 2/0 bare, stranded copper conductor around the perimeter of the raised to form a closed loop. Then I construct a grid of # 4 AWG, bare stranded copper conductors on 2-foot centers inside the perimeter cable. I “H” tap the grid conductors to the perimeter cable, and at each intersection of the grid I use a pipe stand clamp to bond the grid conductor to each other and to the pipe stanchions that support the raised floor grid. Then on the perimeter cable around the room, I “H” tap a # 6 AWG to the perimeter cable and bond it to the stringers of the raised floor at every pedestal using a two-hole compression lug bolted to the stringers. That completes the construction of the grid.

After the grid is constructed I bond it everyplace where is passes by building steel, water pipes, conduits, etc. I then bond the perimeter cable to any and all sub-panels ground buses in the room. In addition I run a 2/0 AWG insulated conductor from the two opposite corners of the perimeter cable back too the service entrance GEC.

For the PDU’s I bond to the nearest building steel under the raised floor. Then as equipment racks are installed they have a #6 AWG bonded from the equipment frame with a 2-hole compression lug back to the SRG with either a “H” or “C” tap. Keep in mind this not to replace any EGC’ required to be ran with phase conductors from the PDU. It is a signal reference ground, not a fault clearing ground. However it will aid in clearing a fault.

There are several methods you can use. As already mentioned you can purchase the IEEE Emerald book or download FIP’s-94 document and/or Grounding Sensitive Equipment by ITIC at http://www.mikeholt.com/freestuff.php?id=freegeneral. But they all follow the same basic guidelines. Good luck. Dereck


#23941 - 03/31/03 04:50 PM Re: Raised Floor  
electrician02125  Offline
Member
Joined: Feb 2001
Posts: 89
Nice job guys

Thanks a million



Member Spotlight
RonKipperDatacom
RonKipperDatacom
Kansas City, KS
Posts: 30
Joined: January 2013
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.009s Queries: 14 (0.001s) Memory: 0.7595 MB (Peak: 0.8901 MB) Zlib enabled. Server Time: 2017-04-24 07:29:37 UTC